Administration apparatus for medical use

ABSTRACT

An expansion/compression mechanism of a piston rod assembly is composed of a bush shaft, a first cylindrical piston rod that is screwed with the bush shaft, a second cylindrical piston rod that is screwed with the first piston rod, and a piston rod holding member for housing the bush shaft and the piston rods. Therefore, the piston rods move linearly in multiple stages, whereby the size of the whole apparatus is reduced.

FIELD OF THE INVENTION

The present invention relates to an administration apparatus for medical use which is driven by an electric driving source to perform administration of a drug and, more particularly, to an administration apparatus that facilitates replacement of drug cartridges.

BACKGROUND OF THE INVENTION

A patient addicted to insulin must get plural times of injections of insulin per week or day. The required amount of insulin varies from patient to patient. The required amount of insulin for each patient varies from injection to injection, and it also varies from day to day.

A patient who performs injection by himself attaches a drug cartridge containing a drug to an injector, and attaches a needle assembly to an elastic seal of the drug cartridge, and thereafter, sets the dose, and operates the injector to inject the drug into his body. The drug in the drug cartridge runs out when such administration is carried out a few times. The patient detaches the empty drug cartridge from the injector, and attaches a new drug cartridge to repeat the above-mentioned injection. As for the conventional injector, when the drug cartridge is replaced with a new cartridge, a member that holds the drug cartridge (hereinafter referred to as a cartridge holder) is detached from the body of the injector, and the drug cartridge is detached from the cartridge holder. Then, a new drug cartridge is inserted into the cartridge holder, and thereafter, the cartridge holder is attached to the injector (for example, Japanese Utility Model Registration No. 3088706).

Although the above-mentioned conventional injector is a hand-operated injector, there is a motor-operated injector as shown in FIG. 24. FIG. 24 is a diagram illustrating the inner structure of a motor-operated injector which is currently popular for dental use. The principle of drug administration will be described with reference to FIG. 24. A syringe 203 filled with a drug is set in a cartridge holder 202 attached to a body 210.

When a switch SW1 is pressed, a motor 211 rotates forward, and the rotation force is decelerated by a deceleration gear box 209 that is directly connected to the motor 211, whereby a deceleration gear main shaft 208 of the deceleration gear box 209 is rotated. An end of the deceleration gear main shaft 208 is engaged with a gear 206 via a rotation plank 207, whereby the gear 206 is rotated. Further, since the gear 206 is engaged with a gear 205, the rotation force of the gear 206 propagates to the gear 205. A gear 205 a is located coaxially with the gear 205 so as to be engaged with a rack 204 a that is provided on the lower right half of an extrusion piston 204. When the gear 205 rotates, the gear 205 a also rotates in the same direction as the gear 205, and consequently, the extrusion piston 204 moves toward an injection needle 213, whereby the drug in the syringe 203 is pressed out of the injection needle 213.

During injection, after performing air releasing in the above-mentioned operation, the injection needle 213 is inserted into a target area, and the drug is administered. In FIG. 24, SW2 denotes a switch for rotating the motor 211 in the reverse order, and 212 denotes a battery for driving the motor 211.

Further, it is very important for an insulin injector to be portable, and therefore, a compact and light-weight injector is desired. The conventional injector is generally provided with a linear piston having a stroke that enables injection of all drug in the drug cartridge. However, there is an injector provided with a curvature type piston (for example, Japanese Published Patent Application No. 2000-513974).

By the way, when a patient actually uses an injector, the patient desires easy replacement of drug cartridges.

In the conventional injector, however, the patient must detach the cartridge holder into which the drug cartridge is inserted from the body of the injector, detach the drug cartridge from the cartridge holder, attach a new drug cartridge to the holder, and mount the cartridge holder onto the injector body, resulting in inconvenient and troublesome operation.

Further, in the case of the injector having a linear piston, the piston must have a stroke that enables injection of all drug in the drug cartridge, and the length of the piston becomes approximately equal to the entire length of the drug cartridge. Therefore, the length of the injector itself becomes at least two times as long as the drug cartridge, leading to an increase in the size of the injector. Further, in the case of the injector having a curvature type piston, the length of the injector becomes shorter than that of the linear piston rod. However, since the piston has a curvature, the thickness of the injector is increased, leading to a disadvantage in handleability.

Furthermore, in the conventional administration apparatus for medical use shown in FIG. 24, although the operation is easy because drug injection is motor-operated, the patient might be anxious as to whether the motor-operated injector including a drive mechanism such as a motor is normally operated or not. The act of drug administration itself gives mental stress onto the patient, and furthermore, abnormal operation of the motor-operated injector greatly affects the human body, which may endanger the life of the patient.

The conventional administration apparatus for medical use is constructed as described above, and the operation of cartridge replacement is troublesome.

Further, the size of the apparatus is too large to handle.

Furthermore, as for the motor-operated apparatus, the patient might be anxious during drug administration about air releasing before injection, the operation state of the mechanism, or the like.

SUMMARY OF THE INVENTION

The present invention is made to solve the above-described problems and has for its object to provide an administration apparatus for medical use which enables a patient to easily replace cartridges, and minimizes the size of an injector itself.

It is another object of the present invention to provide an administration apparatus for medical use which eases physical and mental pains on a patient by detecting abnormal operation during injection and informing it to a patient, thereby enabling the patient to carry out administration of a drug with high stability.

Other objects and advantages of the invention will become apparent from the detailed description that follows. The detailed description and specific embodiments described are provided only for illustration since various additions and modifications within the scope of the invention will be apparent to those of skill in the art from the detailed description.

According to a first aspect of the present invention, an administration apparatus for medical use includes a drug cartridge having an end closed with a plunger, and containing a drug inside; a cartridge holder for holding the drug cartridge; a needle holder which is provided at an end of the cartridge holder slidably in the axial direction of the cartridge holder, and is swingable with respect to the axial direction at its sliding end portion; and a needle assembly for inserting a needle into a target region, and administrating the drug that is ejected from the other end of the drug cartridge by a movement of a piston rod that presses the plunger in the drug cartridge, said needle assembly being detachably provided onto the needle holder; wherein the needle holder is slid in the axial direction of the cartridge holder as well as it is swung with respect to the axial direction at its sliding end portion, thereby exposing a front end portion of the drug cartridge at the front end of the cartridge holder to detach the drug cartridge from the cartridge holder. Therefore, the drug cartridge can be detached or attached from/to the cartridge holder with the cartridge holder being held by the administration apparatus, thereby facilitating cartridge replacement.

According to a second aspect of the present invention, in the administration apparatus for medical use according to the first aspect, detaching of the drug cartridge is possible in a state where the needle assembly is attached to the needle holder. Therefore, handling is facilitated.

According to a third aspect of the present invention, in the administration apparatus for medical use according to the first aspect, the needle holder is provided with a lever for moving the drug cartridge toward the piston rod with the operation of attaching the needle assembly to the needle holder. Therefore, it is possible to check whether the needle assembly is attached or not by detecting the state of the lever.

According to a fourth aspect of the present invention, in the administration apparatus for medical use according to the first aspect, the cartridge holder is provided with a force-applying member for pushing the drug cartridge toward the needle holder. Therefore, it is possible to check whether the needle assembly and the drug cartridge are attached or not by detecting the position of the force-applying unit attached to the cartridge holder.

According to a fifth aspect of the present invention, in the administration apparatus for medical use according to the first aspect, when replacing the drug cartridge, the piston rod is moved back to its initial position with the operation of moving the needle holder toward the position where the needle assembly is attached. Therefore, the piston rod can be returned to the initial position when replacing the cartridge, leading to improved operability.

According to a sixth aspect of the present invention, in the administration apparatus for medical use according to the first aspect further includes a movable target-region contact cover that covers the peripheral side surface of the needle holder, and only a needle of the needle assembly is exposed from the target-region contact cover when performing injection. Therefore, the periphery of the needle holder is covered with the target-region contact cover except when performing injection, thereby preventing a danger such that the needle is inserted by mistake.

According to a seventh aspect of the present invention, in the administration apparatus for medical use according to the sixth aspect, when replacing the drug cartridge, the target-region contact cover is moved to the position where the needle holder is exposed. Therefore, the user can easily touch the needle holder when replacing the drug cartridge, leading to improved operability.

According to an eighth aspect of the present invention, the administration apparatus for medical use according to the sixth aspect further includes a unit for detecting the position of the target-region contact cover. Therefore, an accident such that the needle is inserted by mistake during use can be effectively avoided.

According to a ninth aspect of the present invention, an administration apparatus for medical use includes a drug cartridge having an end closed with a plunger, and containing a drug inside; a cartridge holder for holding the drug cartridge; and a piston rod assembly having plural stages of expansion/compression mechanisms, and pushing the plunger in the drug cartridge to move the plunger. Since the motion of the piston rod is linear in plural stages, the size of the apparatus is significantly reduced, thereby providing an administration apparatus for medical use having excellent portability.

According to a tenth aspect of the present invention, in the administration apparatus for medical use according to the ninth aspect, the plural stages of expansion/compression mechanisms of the piston rod assembly have plural stages of piston rods which are linearly slidable in parallel to the axial direction of the cartridge holder, and the length of each piston rod is shorter than the whole length of the drug cartridge. Since the motions of the piston rods are linear in plural stages, the size of the apparatus is significantly reduced, thereby providing an administration apparatus for medical use having excellent portability.

According to an eleventh aspect of the present invention, in the administration apparatus for medical use according to the tenth aspect, the plural piston rods are concentrically arranged, and the piston rods are successively slid from the piston rod that is positioned at the outermost concentric circle. Since the motions of the piston rods are linear in plural stages, the size of the apparatus is significantly reduced, thereby providing an administration apparatus for medical use having excellent portability.

According to a twelfth aspect of the present invention, an administration apparatus for medical use which performs administration of a drug using an electric driving source, comprises a drug cartridge having an end closed with a plunger, and containing a drug inside; a cartridge holder for holding the drug cartridge; a piston rod for pressing the plunger held in the drug cartridge to move the plunger; a needle assembly for inserting a needle into a target region, and administering the drug that is emitted from the other end of the drug cartridge with a movement of the piston rod; and a control circuit for controlling an air releasing operation for the drug cartridge and/or the injection needle so that the air releasing operation is carried out at a speed lower than the speed of drug administration. Therefore, it is possible to reduce the risk of the drug adhered to the injection needle or the like being splattered when the user visually checks air releasing, and reduce mental pain due to administration.

According to a thirteenth aspect of the present invention, in the administration apparatus for medical use according to the twelfth aspect, the air releasing operation is carried out with the movement of the piston rod. Therefore, the air releasing operation is facilitated.

According to a fourteenth aspect of the present invention, in the administration apparatus for medical use according to the thirteenth aspect, during the air releasing operation, the piston rod is moved at a speed lower than the speed of the piston rod during drug administration. Therefore, it is possible to reduce the risk of the drug adhered to the injection needle or the like being splattered when the user visually checks air releasing, and reduce mental pain due to administration.

According to a fifteenth aspect of the present invention, in the administration apparatus for medical use according to the fourteenth aspect, the low-speed operation of the piston rod during the air releasing operation is performed by PWM (Pulse Width Modulation) control for controlling the piston rod with the ON-OFF ratio of the pulse width being varied. Therefore, it is possible to reduce the risk of the drug adhered to the injection needle or the like being splattered when the user visually checks air releasing, and reduce mental pain due to administration.

According to a sixteenth aspect of the present invention, in the administration apparatus for medical use according to the fourteenth aspect, the low-speed operation of the piston rod during the air releasing operation is performed by voltage control. Therefore, it is possible to reduce the risk of the drug adhered to the injection needle or the like being splattered when the user visually checks air releasing, and reduce mental pain due to administration.

According to a seventeenth aspect of the present invention, an administration apparatus for medical use which performs administration of a drug using an electric driving source, comprises a drug cartridge having an end closed with a plunger, and containing a drug inside; a cartridge holder for holding the drug cartridge; a piston rod for pressing the plunger in the drug cartridge to move the plunger; a needle assembly for inserting a needle into a target region, and administering the drug that is emitted from the other end of the drug cartridge with a movement of the piston rod; and a control circuit for performing control so that an air releasing operation for the drug cartridge and/or the injection needle is always carried out before performing the drug administration operation. Therefore, air releasing is always carried out before drug administration, whereby mental anxiety to machine can be reduced.

According to an eighteenth aspect of the present invention, the administration apparatus for medical use according to the seventeenth aspect further includes an air releasing switch for performing the air releasing operation, and an administration switch for injecting the drug, and the control circuit permits an operation by turn-on of the administration switch after the air releasing operation. Therefore, there is no fear of drug administration when air releasing is not carried out, whereby mental anxiety to machine can be reduced.

According to a nineteenth aspect of the present invention, the administration apparatus for medical use according to the twelfth or seventeenth aspect further includes a contact sensor for detecting whether a portion of the administration apparatus in the vicinity of the needle assembly contacts a target region or not, and the air releasing operation is suppressed when the contact sensor contacts the target region. Therefore, it is possible to prevent an accident such that the needle is inserted into the human body during air releasing, whereby mental anxiety to machine can be reduced.

According to a twentieth aspect of the present invention, an administration apparatus for medical use which performs administration of a drug using an electric driving source, comprises a drug cartridge having an end closed with a plunger, and containing a drug inside; a cartridge holder for holding the drug cartridge; a piston rod for pressing the plunger in the drug cartridge to move the plunger; a needle assembly for inserting a needle into a target region, and administering the drug that is emitted from the other end of the drug cartridge with a movement of the piston rod; a dose setting circuit for setting, by a user, a dose of drug to be administered; a dose holding circuit for holding doses of drug which have been administered in the past; a dose comparison circuit for comparing the dose that is set by the dose setting circuit with the doses that are held in the dose holding circuit; and a control circuit for performing control so as to suppress the operation of the piston rod when the result of comparison by the dose comparison circuit is equal to or larger than a predetermined value. Therefore, the user cannot proceed to the administration step when the dose changes significantly, thereby reducing mental and physical pains caused by use of the motor-operated administration apparatus for medical use.

According to a twenty-first aspect of the present invention, in the administration apparatus for medical use according to the twentieth aspect, the dose holding circuit holds the dose of drug that has been administered most recently, and the dose comparison circuit compares the dose that is set by the user with the dose that has been administered most recently. Therefore, the user cannot proceed to the administration step when the dose changes significantly, thereby reducing mental and physical pains caused by use of the motor-operated administration apparatus for medical use.

According to a twenty-second aspect of the present invention, in the administration apparatus for medical use according to the twentieth aspect, the dose holding circuit holds the doses of drug of plural times of administrations performed in the past, and the dose comparison circuit compares the dose that is set by the user with a dose that is obtained on the basis of the plural times of administrations performed in the past. Therefore, the user cannot proceed to the administration step when the dose changes significantly, thereby reducing mental and physical pains caused by use of the motor-operated administration apparatus for medical use.

According to a twenty-third aspect of the present invention, in the administration apparatus for medical use according to the twenty-second aspect, the dose obtained on the basis of the plural times of administrations performed in the past is an average of doses of the plural times of administrations in the past. Therefore, the user cannot proceed to the administration step when the dose changes significantly, thereby reducing mental and physical pains caused by use of the motor-operated administration apparatus for medical use.

According to a twenty-fourth aspect of the present invention, the administration apparatus for medical use according to the twentieth aspect further includes a notification unit for notifying the user that administration is not possible, when the result of comparison by the dose comparison circuit is equal to or larger than the predetermined value. When the dose changes significantly, it is informed to the user and then the user confirms the dose, thereby reducing mental and physical pains caused by use of the motor-operated administration apparatus for medical use.

According to a twenty-fifth aspect of the present invention, in the administration apparatus for medical use according to the twenty-fourth aspect, when the user permits administration of the dose of drug that is set by the user is permitted after notifying the user that administration is not possible using the notification unit, the control circuit cancels restriction on the operation of the piston rod. Therefore, even when the dose changes significantly, the user can perform administration for his own convenience. Since the dose change is informed to the user before administration and then the user can check the dose, mental and physical pains caused by use of the motor-operated administration apparatus for medical use can be reduced.

According to a twenty-sixth aspect of the present invention, an administration apparatus for medical use which performs administration of a drug using an electric driving source, comprises a drug cartridge having an end closed with a plunger, and containing a drug inside; a cartridge holder for holding the drug cartridge; a piston rod for pressing the plunger held in the drug cartridge to move the plunger; a needle assembly for inserting a needle into a target region, and administering the drug that is emitted from the other end of the drug cartridge with a movement of the piston rod; a dose setting circuit for setting, by a user, a dose of drug to be administered; a dose detection circuit for detecting an actual dose of drug using an electronic circuit; and a comparison detection circuit for comparing the dose that is set by the dose setting circuit with the result of detection by the dose detection circuit to detect overdose or underdose of the drug. Therefore, it is possible to monitor the actual dose of drug by the electronic circuit as well as to monitor the dose of drug by the program for setting the dose in advance, and injection of overdose or underdose of the drug can be prevented by forced stop or the like even when the program is operated abnormally, thereby reducing mental and physical pains caused by use of the motor-operated administration apparatus.

According to a twenty-seventh aspect of the present invention, in the administration apparatus for medical use according to the twenty-sixth aspect, the comparison detection circuit stops the piston rod when it detects overdose of the drug, thereby to stop administration. Therefore, it is possible to prevent overdose of drug even when the program is abnormally operated, reducing mental and physical pains caused by use of the motor-operated administration apparatus for medical use.

According to a twenty-eighth aspect of the present invention, in the administration apparatus for medical use according to the twenty-sixth aspect, the dose detection circuit detects the dose on the basis of the amount of movement of the piston rod. Therefore, the actual dose of drug can be detected by the electronic circuit.

According to a twenty-ninth aspect of the present invention, in the administration apparatus for medical use according to the twenty-sixth aspect, the dose detection circuit detects the dose on the basis of the time when the piston rod moves at a constant speed. Therefore, the actual dose of drug can be detected by the electronic circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating the whole of an administration apparatus for medical use according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a part of the administration apparatus in the vicinity of a needle holder, for explaining replacement of drug cartridges.

FIG. 3 is a diagram illustrating the state where the needle holder is drawn from the body of the administration apparatus, for explaining replacement of drug cartridges.

FIG. 4 is a diagram illustrating the state where the drug cartridge is detached from the body, for explaining replacement of drug cartridges.

FIG. 5 is an enlarge view of a main part of the needle holder in the administration apparatus for medical use.

FIG. 6 is an enlarge view of the main part of the needle holder for explaining the operation of the needle holder.

FIG. 7 is a diagram illustrating the state where the needle holder is slid, for explaining the operation of the needle holder.

FIG. 8 is a diagram illustrating a piston rod assembly of the administration apparatus for medical use.

FIG. 9 is a diagram for explaining the state of a detection lever when attaching a needle assembly onto the needle holder of the administration apparatus.

FIG. 10 is a diagram illustrating the construction of a part of the administration apparatus in the vicinity of a rear end of the drug cartridge.

FIG. 11 is a diagram illustrating the construction of a main part of a piston rod assembly of an administration apparatus for medical use according to a second embodiment of the present invention.

FIG. 12 is a diagram illustrating the state where the piston rod assembly of the administration apparatus according to the second embodiment is housed in a piston rod holding member.

FIG. 13 is a diagram for explaining the operation of the piston rod assembly of the administration apparatus according to the second embodiment.

FIG. 14 is a diagram for explaining the operation of the piston rod assembly of the administration apparatus according to the second embodiment.

FIG. 15 is a cross-sectional view for explaining the engagements of a bush shaft and the respective piston rods of the administration apparatus according to the first embodiment.

FIG. 16 is a perspective view illustrating the internal structure of an administration apparatus for medical use according to a third embodiment of the present invention.

FIG. 17 is a perspective view illustrating the external appearance of the administration apparatus according to the third embodiment.

FIG. 18 is a block diagram for explaining connections of components in the administration apparatus according to the third embodiment as an electric circuit.

FIG. 19 is a flowchart for explaining the operation of the administration apparatus according to the third embodiment.

FIG. 20 is a flow chart for explaining an administration apparatus for medical use according to a fourth embodiment of the present invention.

FIG. 21 is a block diagram for explaining connections of components in an administration apparatus for medical use according to a fifth embodiment of the present invention as an electric circuit.

FIG. 22 is a flow chart for explaining the operation of the administration apparatus according to the fifth embodiment.

FIG. 23 is a block diagram for explaining connections of components in an administration apparatus for medical use according to a sixth embodiment as an electric circuit.

FIG. 24 is a diagram illustrating the construction of the conventional administration apparatus for medical use.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

FIG. 1 is a diagram illustrating the whole construction of an administration apparatus for medical use according to a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes an administration apparatus having, at an end thereof, a target-region contact cover 7 to be applied to a target region of patient's body to be subjected to injection when the patient performs administration by himself, and a needle assembly 6 is housed in the cover 7.

Further, a drug cartridge containing a drug, an end of which is closed with a plunger (not shown), is inserted in the administration apparatus. When the needle assembly 6 pierces the target region, a piston rod (not shown) that presses the plunger moves, whereby the drug emitted from an end of the drug cartridge is injected into the patient's body.

When the patient replaces the drug cartridge, the target-region contact cover 7 is slid in the direction of arrow A as shown in FIG. 2, whereby the needle assembly 6 attached to a needle holder 4 is exposed. Usually, cartridge replacement should be carried out after a protection cover (not shown) is put on the needle assembly 6 to avoid an accident of error insertion of the needle assembly 6. However, description of the protection cover is omitted.

Next, as shown in FIG. 3, the needle holder 4 is slid in the direction of arrow B. The needle holder 4 is moved up to a predetermined position, and then the needle holder 4 is swung about a shaft (not shown), whereby the drug cartridge 2 is exposed from the administration apparatus 1. Thereafter, the patient detaches the drug cartridge 2.

The outline of cartridge replacement is as described above. Hereinafter it will be described in more detail using FIGS. 5 to 7.

In FIG. 5, support struts 9 are provided on the both sides of the front end of the cartridge holder 3 which holds the drug cartridge 2. Further, the needle holder 4 to which the needle assembly 6 is attached has grooves 8 for slide-guiding the support struts 9, and the needle holder 4 and the cartridge holder 3 are joined to each other by the respective grooves 8 and support struts 9.

When the patient replaces the drug cartridge 2, as shown in FIG. 6, the target-portion contact cover 7 (refer to FIG. 2) is moved up to a predetermined position, and the needle holder 4 is slid in the direction of arrow B until the rear portion of the groove 8 contacts the support strut 9. When the needle holder 4 reaches the predetermined position, the needle holder 4 swings about the support strut 9 as shown in FIG. 7, and a front end 2 a of the drug cartridge 2 is exposed at the front end of the cartridge holder 3.

Thereafter, replacement of the drug cartridge 2 can be carried out. After a new drug cartridge 2 is attached, the administration apparatus 1 is set in the injection-ready state by performing the reverse of the above-mentioned operation.

Further, during injection, only the needle portion of the needle assembly is exposed out of the contact cover. Therefore, at all other times, the periphery of the needle holder is covered, thereby preventing an accident such as needle insertion by mistake.

Further, a means for detecting the position of the contact cover may be provided to prevent an accident such as needle insertion by mistake during use. To be specific, the contact cover is detected by a position detection means that is provided in the administration apparatus when the contact cover is in the used position.

Next, the drug cartridge holding state will be described with reference to FIGS. 8 to 10.

A detection lever 18 is attached to the needle holder 4. FIG. 9 shows the state of the detection lever 18 in the case where the needle assembly 6 is attached to the needle holder 4 (refer to FIG. 8). When the needle assembly 6 is attached to the needle holder 4, a rear end portion of the needle assembly 6 presses the detection lever 18, and a rear end portion of the detection lever 18 presses the front end portion 2 a of the drug cartridge 2. Further, as shown in FIG. 10, the rear end portion 2 b of the drug cartridge 2 is pressed by a press member 19 that is slidably attached to the periphery of a piston rod hold member 16.

The press member 19 comprises a spring member 20 and a stopper member 21.

In the above-mentioned construction, presence/absence of the needle assembly 6 and the drug cartridge 2 can be detected by detecting the position of the press member 19.

Further, when replacing the drug cartridge, the needle holder 4 is moved in the direction in which the needle assembly 6 is attached, by the detection lever 18 and the piston rod holding member 16, whereby the piston rod is moved back to the initial position. Thus, operability during cartridge replacement is improved.

As described above, in the first embodiment of the present invention, since the front end of the drug cartridge 2 is exposed by drawing the needle holder 4 from the body of the administration apparatus 1 and swinging the holder 4, the drug cartridge 2 is detachable with the cartridge holder 3 being held by the administration apparatus 1. Therefore, in contrast to the conventional administration apparatus, the patient is free from the burden that the patient must separate the cartridge holder from the administration apparatus body every time the patient replaces the cartridge. Further, the patient can arbitrarily carry out replacement of the drug cartridge regardless of the needle assembly attachment state, thereby facilitating handling.

The administration apparatus for medical use according to the present invention is applicable to both of a hand operated administration apparatus and a motor-operated administration apparatus.

Embodiment 2

Next, an administration apparatus for medical use according to a second embodiment of the present invention will be described. FIG. 11 is a diagram illustrating a piston rod assembly of a motor-operated administration apparatus for medical use according to a second embodiment of the present invention. As shown in FIG. 11, a bush shaft 11 having a length approximately equal to the whole length of the rod assembly and having a male thread (not shown) on its periphery is pushed into a driving gear 10 for transferring a driving power from a motor or the like (not shown). Further, a hollow piston rod A12 having, on its inner periphery, a female thread (not shown) that is screwed with the male thread of the bush shaft 11 has a male thread (not shown) on its periphery. Furthermore, a piston rod B14 having, on its inner periphery, a female thread (not shown) that is screwed with the piston rod A12 is screwed with the piston rod A12. How the bush shaft 11, the piston rod A12, and the piston rod B14 are screwed is shown in FIG. 15.

Further, the piston rod A12 and the piston rod B14 are provided with convex-shaped rotation prevention parts 13 and 15, respectively. Further, as shown in FIG. 12, the piston rod B14 is covered with a hollow piston rod holding member 16 that allows the piston rod B14 to slide smoothly. Further, a concave-shaped piston rod rotation prevention part 17 which contacts the rotation prevention parts 13 and 15 of the piston rod A12 and the piston rod B14 to prevent the piston rods A12 and B14 from rotating, respectively, is provided in the piston rod holding member 16.

Next, the actual operation will be described with reference to FIGS. 12 to 14. First of all, FIG. 12 shows the initial state, wherein the rotation prevention part 13 of the piston rod A12 is positioned outside the piston rod holding member 16. The driving force of the driving gear 10 is transferred to the bush shaft 11 and the piston rod A12, and the driving gear 10, the bush shaft 11, and the piston rod A12 rotate in one direction in synchronization with each other.

Further, since the rotation prevention part 15 of the piston rod B14 cannot rotate because it contacts the piston rod rotation prevention part 17 of the piston rod holding member 16, the rotation force transferred from the piston rod A12 to the piston rod B14 is converted into a driving force for moving the piston rod B14 forward, whereby the piston rod B14 slides in the direction of arrow A as shown in FIG. 13. The male thread on the periphery of the piston rod A12 is not formed over the entire length, but a portion of a few millimeters from the opposite side of the rotation prevention part 13 is an imperfect thread portion. Accordingly, rotation of the piston rod A12 stops when the imperfect thread of the piston rod A12 reaches the thread of the piston rod B14.

Since the rotation prevention part 15 of the piston rod B14 still contacts the piston rod rotation prevention part 17 of the piston rod holding member 16, the piston rod A12 that has stopped rotation slides in the direction of arrow A in synchronization with the piston rod B14. Further, the instant when the rotation prevention part 15 of the piston rod B14 is apart from the piston rod rotation prevention part 17 of the piston holding member 16, the rotation prevention part 13 of the piston rod A12 contacts the piston rotation prevention part 17 of the piston holding member 16, and therefore, the piston rod B14 slides in the drug cartridge 2 in synchronization with the sliding of the piston rod A12 (refer to FIG. 14). Then, the plunger of the drug cartridge 2 is pressed, whereby the drug is drained. The piston rod can be returned to the initial state by performing the reverse of the above-mentioned processing.

As described above, in the administration apparatus for medical use according to the second embodiment, the expansion/compression mechanism of the piston rod assembly is composed of the bush shaft 11, the cylindrical piston rod A12 that is screwed with the bush shaft 11, the cylindrical piston rod B14 that is screwed with the piston rod A12, and the piston rod holding member 16 that stores these piston rods, whereby the motion of the piston rods is expanded linearly in plural stages to make the apparatus very compact, resulting in an administration apparatus for medical use having excellent portability.

While in this second embodiment the motor-operated administration apparatus for medical use has been described, the present invention is not restricted thereto. For example, a hand-operated administration apparatus for medical use which manually drives a driving gear 10 using a spring or the like is also within the scope of the present invention.

Embodiment 3

Next, an administration apparatus for medical use according to a third embodiment of the present invention will be described with reference to FIGS. 16 to 19.

FIG. 16 is a perspective view for explaining the internal structure of an administration apparatus for medical use according to the third embodiment, FIG. 17 is a perspective view illustrating the external appearance of the administration apparatus, FIG. 18 is a block diagram for explaining connections in the administration apparatus as an electric circuit, and FIG. 19 is a flowchart for explaining the operation of the administration apparatus.

Initially, FIG. 16 will be described.

FIG. 16 is a diagram illustrating the construction of a motor-operated administration apparatus for medical use which performs an operation of administrating a drug using an electric driving source.

In FIG. 16, a syringe (drug cartridge) 101 filled with a drug is set in a cartridge holder 103 that is attached to a body 102 of the apparatus.

A user holds the body 102 with hand, presses a contact sensor against a region to which the drug should be administered, and pushes an administration switch 104 that is provided on the side surface of the body 102. Then, a needle-insertion motor 105 rotates forward, and this rotation force propagates to a slide cap 107 through a slide rod 106 that is directly connected to the needle-insertion motor 105. The rotation force of the needle-insertion motor 105 is converted into a force of linear motion by the slide cap 107. The slide cap 107 moves in the direction of the arrow when the needle-insertion motor 105 rotates forward. A needle-removal sensor is turned off as the slide cap 107 starts to move. The slide cap 107 moves by a predetermined amount in the direction of the arrow. At this time, a needle-insertion sensor 109 is turned on, and rotation of the needle-insertion motor 105 stops.

The slide cap 107 is coupled to an inner frame assembly part 110. When the needle-insertion motor 105 rotates forward, the inner frame assembly part 110 moves in the direction of the arrow. The inner frame assembly part 110 is coupled to an injection assembly part 111. The injection assembly part 111 moves in the direction of the arrow when the needle-insertion motor 105 rotates forward, and inserts an injection needle 112 into the target region.

After the needle-insertion operation, an injector motor 113 rotates forward, and this rotation force is decelerated by a deceleration gear box 114 directly connected to the injection motor 113, whereby a gear main shaft 115 of the deceleration gear box 114 is rotated. The front end of the gear main shaft 115 rotates a primary gear 116. This rotation force propagates to a tertiary gear 118 through a secondary gear 117. The tertiary gear 118 is coupled to a primary rod 119. Since the primary rod 119 is engaged with a secondary rod 120, the rotation force of the primary rod 119 propagates to the secondary rod 120. Since the secondary rod 120 is engaged with a tertiary rod 121, the rotation force of the secondary rod 120 propagates to the tertiary rod 121. The rotation force of the tertiary rod 121 is restricted by a groove that is provided inside the cartridge holder 103, and the tertiary rod 121 moves in the direction of the arrow. When the tertiary rod 121 moves ahead in the syringe 101 by a predetermined amount, the secondary rod 120 that has rotated also pushes the syringe 101. Then, the tertiary rod 121 pushes a plunger in the syringe 101 so that the drug is pushed out of the injection needle 112, whereby injection operation is carried out. The dose is adjusted by counting the rotation of the injection motor 113 by a rotation sensor 122.

The primary rod 119, the secondary rod 120, and the tertiary rod 121 have the same construction as the piston rod assembly described for the first embodiment.

After the injection operation, the injection motor 113 rotates backward to return the secondary rod 120 and the tertiary rod 121 back to the initial positions. Thereafter, the needle-insertion motor 105 rotates backward to move the slide cap 107 in the direction opposed to the arrow. The slide cap 107 is coupled to the inner frame assembly pat 110. When the needle-insertion motor 105 rotates backward, the inner frame assembly part 110 rotates in the direction opposed to the arrow. The inner frame assembly part 110 is coupled to the injection assembly part 111. Accordingly, the injection assembly part 111 moves in the direction opposed to the arrow together with the inner frame assembly part 110 when the needle-insertion motor 105 rotates backward, whereby the injection needle 112 is removed from the target region.

When the slide cap 107 returns to the initial position, the needle-removal sensor 108 is turned on to stop the needle-insertion motor 105, whereby the needle removal operation is completed.

Next, the external construction of the administration apparatus for medical use according to the present invention will be described with reference to FIG. 17.

In FIG. 17, reference numeral 123 denotes a power source switch for turning the power on when using the administration apparatus, and turning the power off after use.

Reference numeral 124 denotes an air releasing switch for starting air releasing in the syringe or injection needle.

Reference numeral 125 is a setting switch for setting such as the dose of drug to be injected into the body.

Reference numeral 126 denotes a contact sensor for checking whether the administration apparatus contacts the region to be subjected to administration or not.

Reference numeral 127 denotes a display unit for displaying the set dose of drug to be injected into the body, and the condition in the administration apparatus, for example, the amount of remaining drug. Further, the display unit 127 notifies the user of abnormal operation or the like.

Reference numeral 128 denotes an injection needle port as an opening through which the injection needle passes during needle insertion and needle removal.

Next, the electrical circuit construction of the administration apparatus having the constructions shown in FIGS. 16 and 17 will be described with reference to FIG. 18. In FIG. 18, the same reference numerals as those shown in FIGS. 16 and 17 denote the same or corresponding parts.

Reference numeral 129 denotes a speaker for notifying the user of the end of operation, abnormal operation, or the like by voice.

Reference numeral 132 denotes an origin point sensor for detecting that the piston for injecting the drug in the syringe is positioned in the origin point.

Reference numeral 131 denotes a motor driver for outputting a signal for driving the injection motor 113 and the needle-insertion motor 105 according to a command from a microprocessor 130.

The microprocessor 130 is a controller which outputs a command for operating the injection motor 113 or the needle-insertion motor 105 by turning on the air releasing switch or the administration switch 104 according to a program.

Next, the sequence of air releasing and drug injection by the microprocessor 130 of the administration apparatus according to the third embodiment will be described with reference to the flowchart shown in FIG. 19. When the air releasing switch 124 or the administration switch 104 is pressed, the sequence starts (step a1).

Next, it is judged whether the air releasing switch 124 is pressed or not (step a2). When the air releasing switch 124 is pressed, the process goes to step a3.

In step a3, the needle-insertion motor 105 is operated at a low speed using a reduction in the driving voltage, or PWM (Pulse Width Modulation) control for changing the ON/OFF ratio of the pulse width of the signal, during a period from when the needle-removal sensor 108 is turned on to when the needle-insertion sensor 109 is turned on. Next, in step a4, the injection motor 113 is rotated forward by an amount required for air releasing, and air releasing is carried out by moving the piston rods 119˜121.

Next, in step a5, the needle-insertion motor 105 is rotated backward at a low speed to move the injection needle up to a position where the needle-insertion sensor 109 is on, thereby completing the processing (step a9).

On the other hand, when not the air releasing switch 124 but the administration switch 104 is pushed in step a2, the process goes to step a6. In step a6, needle insertion is carried out at a high speed to reduce the pain of the patient associated with the needle insertion.

Next, in step a7, the injection motor 113 is operated to inject a set dose of drug.

Next, in step a8, after the injection is ended, the needle-insertion motor 105 is rotated in the reverse direction at a high speed to move the injection needle from the position of the needle-insertion state to the position of the needle-removal state, thereby completing the processing (step a9).

As described above, in the administration apparatus for medical use according to the third embodiment, when the air releasing switch 124 is pressed using the plural piston rods 119 to 121, air releasing can be easily carried out by the motor with the movements of the piston rods 119 to 121. Further, since the injection motor 113 is operated at a low speed during air releasing, it is possible to reduce the risk of the drug adhered to the injection needle or the like being splattered when the user visually checks air releasing.

Embodiment 4

Next, an administration apparatus for medical use according to a fourth embodiment of the present invention will be described. The administration apparatus according to the fourth embodiment always performs air releasing of the drug cartridge and/or the injection needle before performing drug administration to increase the level of safety of the apparatus. The construction of the apparatus according to the fourth embodiment is identical to that described with respect to FIGS. 16 to 18 and, therefore, repeated description is not necessary.

Hereinafter, the operation of the microprocessor 130 of the administration apparatus for medical use according to the fourth embodiment will be described with reference to FIG. 20.

When the air releasing switch 124 or the administration switch 104 is pressed, the sequence is stated (step b1).

Initially, it is judged whether the air releasing switch 124 is pressed or not (step b2). When the pressed switch is not the air releasing switch 124 but the administration switch 104, step b2 is carried out again. When the pressed switch is the administration switch 104, since administration is not carried out, it is informed to the user that the administration switch 104 is pressed, using the speaker 129 by voice or using the display unit 127, or using both of the speaker 129 and the display device 127.

On the other hand, when the air releasing switch 124 is pressed in step b2, the process goes to step b3. In step b3, it is judged whether the contact sensor 126 is on or not. Since there is a danger that the needle might be inserted into the user by mistake when the contact sensor 120 is on, step b3 is carried out again. At this time, since air releasing is not carried out when the contact sensor 126 is on, it is informed to the user that the contact sensor 126 is on, using the speaker 129 by voice or using the display device 127, or using both of the speaker 129 and the display unit 127.

On the other hand, when the contact sensor 126 is on in step b3, the process goes to step b4. In step b4, the injection motor 113 is driven to release the air in the syringe 101 or the injection needle 112.

Next, the user visually checks whether air releasing is satisfactorily carried out or not, and presses the air releasing switch 124 again when it is not satisfactorily carried out.

When air releasing is carried out satisfactorily, the administration switch 104 is pressed. In step b5, it is judged which of the administration switch 104 and the releasing switch 124 is pressed. When the air releasing switch 124 is pressed, the process goes to step b3. When the administration switch 104 is pressed, the process goes to step b6.

In step b6, it is judged whether the contact sensor 126 is on or not. When the contact sensor 126 is not on, there is a possibility that the administration apparatus is not in contact with a predetermined target region of the user, and therefore, step b3 is carried out again. Since no injection is carried out when the contact sensor 126 is not on, it is informed to the user that the contact sensor 126 is not on, using the speaker 129 by voice or using the display device 127, or using both the speaker 129 and the display device 127. When the contact sensor 126 is on, the process goes to step b7.

In step b7, the set dose of drug is injected by driving the injection motor 113 to complete the processing (step b8).

As described above, according to the fourth embodiment, the injection operation by pressing the administration switch 104 is enabled after detecting that the air releasing switch 124 is pressed before pressing the administration switch 104, using the plural piston rods 119 to 121. Therefore, air releasing can be carried out with reliability before drug injection to reduce the risk of injecting air into human body, whereby the level of safety of the apparatus is increased.

Embodiment 5

An administration apparatus according to a fifth embodiment of the present invention will be described hereinafter. Since the construction of the administration apparatus according to the fifth embodiment is identical to that described with respect to FIGS. 16 to 18, repeated description is not necessary.

Hereinafter, the electrical circuit structure of the administration apparatus according to the fifth embodiment will be described.

FIG. 21 is a block diagram illustrating the construction shown in FIG. 18 to which a setting circuit 133, a dose comparison circuit 134, and a dose holding circuit 135, which are components peculiar to the fifth embodiment, are added, and the display unit 127 and the speaker 129 shown in FIG. 18 are omitted for simplification.

The setting circuit 133 is composed of an electronic circuit capable of holding the amount of operation of the injection motor which is obtained by converting the amount of injection outputted from the microprocessor 130.

The dose holding circuit 135 is composed of an electronic circuit for holding the doses of drug that have been administered in the past. To be specific, it holds the latest dose, or plural doses in the past, or an average of plural doses in the past.

The dose comparison circuit 134 is composed of an electronic circuit for comparing the dose that is set by the setting circuit 133 with the dose (doses) that is held by the dose holding circuit 135.

Next, the operation of the microprocessor 130 of the administration apparatus according to the fifth embodiment will be described with reference to FIG. 22.

When the user stands ready to set a dose, the sequence starts (step c1).

Initially, in step c2, a range of dose is calculated from the past set values that are stored in the dose holding circuit 135. The range of dose according to the past set values may be a range from −30% to +30% of the last dose, or a range that is obtained on the basis of plural doses in the past. For example, using the average of data of past ten doses, a range from −30% to +30% of the average value is set as a range of dose. Moreover, a range of dose may be obtained by statistically calculating data of past ten doses using standard deviation or the like.

Next, in step c3, the user determines an amount of injection and sets the amount on the setting circuit 133.

Subsequently, in step c4, the dose comparison circuit 134 compares the value inputted by the user in step c3 with the value calculated in step c2. When the result of comparison is within the predetermined range, the process goes to step c6. When the result of comparison is out of the predetermined range, the process goes to step c5 to be described later.

In step c5, it is informed to the user that the set value is out of the predetermined range, using the speaker 129 by voice or using the display unit 127, or using both of the speaker 129 and the display unit 127. Then, the user judges whether the process can be shifted to injection step or not. When the user permits shifting to injection step, the process goes to step c7. When the user refuses, the process goes back to step c3.

In step c6, injection of the set dose is carried out by driving the injection motor 113 to complete the process (step c7).

In step c5, after informing the user that the set value is out of the predetermined range using the speaker 129 by voice or the display unit 127 or using both of the speaker 129 and the display unit 127, the process may go to step c3 without confirmation by the user.

As described above, in the administration apparatus for medical use according to the fifth embodiment, when setting a dose using the setting switch 125, the set value is compared with past doses. When the result of comparison is out of a predetermined range, it is informed to the user using the speaker 129 by voice or using the display unit 127, or using both of the speaker 129 and the display unit 127. Depending on the types of drugs, some drug might adversely affect human body if the dose of the drug is significantly different from the proper dose. Therefore, when the dose changes significantly, the change of the dose is informed to the user before administration and then the user confirms the dose, or the user is inhibited to perform administration, whereby the level of safety of the motor-operated administration apparatus for medical use is increased.

Embodiment 6

Next, an administration apparatus for medical use according to a sixth embodiment of the present invention will be described. Since the construction of the administration apparatus according to the sixth embodiment is identical to that described with respect to FIGS. 16 to 18, repeated description is not necessary.

The electrical circuit structure of the administration apparatus according to the sixth embodiment will be described with reference to a block diagram shown in FIG. 23. In FIG. 23, the construction shown in FIG. 18 further includes a setting circuit 133, a comparison detection circuit 136, and a count circuit 137 which are component peculiar to the sixth embodiment, and the display unit 127 and the speaker 129 shown in FIG. 18 are omitted for simplification.

The rotation sensor 122 is able to output the operation of the injection motor 113 as a frequency, and the frequency is output to the microprocessor 130 and the count circuit 137.

The count circuit 137 is composed of an electronic circuit for counting signals from the rotation sensor 122, and it is able to count the amount of operation of the injection motor 113.

The setting circuit 133 is composed of an electronic circuit which is able to hold the amount of operation that is obtained by converting the amount of injection outputted from the microprocessor 130. Further, the setting circuit 133 is able to receive an instruction of injection start or injection end from the microprocessor 130, whereby it can make the count circuit 137 perform initialization.

The dose can be detected by counting the amount of movement of the piston rod or counting the time when the piston rod moves at a constant speed.

The comparison detection circuit 136 is composed of an electronic circuit for comparing the set value of the setting circuit 133 with the count value of the count circuit 137 to detect overdose or underdose of drug. When the count value exceeds a predetermined value with respect to the set value before end of operation, the comparison detection circuit 136 can stop the operation of the motor driver 131, bypassing the microprocessor 130, and it can inform the microprocessor 130 that the predetermined value is exceeded. Further, when the count value is lower than a predetermined value with respect to the set value after the end of operation, the comparison detection circuit 136 can inform the microprocessor 130 that the count value is lower than the predetermined value.

In the above-mentioned construction, it is possible to directly observe the actual dose electronic-circuit-wise by the comparison detection circuit 136, in addition to observing the dose by the program processing using the microprocessor 130. Therefore, even when the program of the microprocessor 130 is operated abnormally, the comparison detection circuit 136 detects the abnormal event to perform a process such as compulsory stopping the motor driver 131, whereby overdose or underdose of drug can be avoided. As a result, double safeguards can be presented, whereby the level of safety of the motor-operated administration apparatus for medical use can be increased.

The administration apparatus for medical use according to the present invention is useful as a motor-operated injection apparatus or the like for a drug such as insulin, which provides easy replacement of drug cartridges and high portability. 

1. An administration apparatus for medical use including: a drug cartridge having an end closed with a plunger, and containing a drug inside; a cartridge holder for holding the drug cartridge; a needle holder which is provided at an end of the cartridge holder slidably in the axial direction of the cartridge holder, and is swingable with respect to the axial direction at its sliding end portion; and a needle assembly for inserting a needle into a target region, and administrating the drug that is ejected from the other end of the drug cartridge by a movement of a piston rod that presses the plunger in the drug cartridge, said needle assembly being detachably provided onto the needle holder; wherein the needle holder is slid in the axial direction of the cartridge holder as well as it is swung with respect to the axial direction at its sliding end portion, thereby exposing a front end portion of the drug cartridge at the front end of the cartridge holder to detach the drug cartridge from the cartridge holder.
 2. An administration apparatus for medical use as defined in claim 1 wherein detaching of the drug cartridge is possible in a state where the needle assembly is attached to the needle holder.
 3. An administration apparatus for medical use as defined in claim 1 wherein the needle holder is provided with a lever for moving the drug cartridge toward the piston rod with the operation of attaching the needle assembly to the needle holder.
 4. An administration apparatus for medical use as defined in claim 1 wherein the cartridge holder is provided with a force-applying member for pushing the drug cartridge toward the needle holder.
 5. An administration apparatus for medical use as defined in claim 1 wherein when replacing the drug cartridge, the piston rod is moved back to its initial position with the operation of moving the needle holder toward the position where the needle assembly is attached.
 6. An administration apparatus for medical use as defined in claim 1 further including a movable target-region contact cover that covers the peripheral side surface of the needle holder, wherein, when performing injection, only a needle of the needle assembly is exposed from the target-region contact cover.
 7. An administration apparatus for medical use as defined in claim 6 wherein when replacing the drug cartridge, the target-region contact cover is moved to the position where the needle holder is exposed.
 8. An administration apparatus for medical use as defined in claim 6 further including a unit for detecting the position of the target-region contact cover.
 9. An administration apparatus for medical use including: a drug cartridge having an end closed with a plunger, and containing a drug inside; a cartridge holder for holding the drug cartridge; and a piston rod assembly having plural stages of expansion/compression mechanisms, and pushing the plunger in the drug cartridge to move the plunger.
 10. An administration apparatus for medical use as defined in claim 9, wherein the plural stages of expansion/compression mechanisms of the piston rod assembly having plural stages of piston rods which are linearly slidable in parallel to the axial direction of the cartridge holder, and the length of each piston rod is shorter than the whole length of the drug cartridge.
 11. An administration apparatus for medical use as defined in claim 10 wherein the plural piston rods are concentrically arranged, and the piston rods are successively slid from the piston rod that is positioned at the outermost concentric circle.
 12. An administration apparatus for medical use which performs administration of a drug using an electric driving source, said apparatus comprising: a drug cartridge having an end closed with a plunger, and containing a drug inside; a cartridge holder for holding the drug cartridge; a piston rod for pressing the plunger held in the drug cartridge to move the plunger; a needle assembly for inserting a needle into a target region, and administering the drug that is emitted from the other end of the drug cartridge with a movement of the piston; and a control circuit for controlling an air releasing operation for the drug cartridge and/or the injection needle so that the air releasing operation is carried out at a speed lower than the speed of drug administration.
 13. An administration apparatus for medical use as defined in claim 12 wherein the air releasing operation is carried out with the movement of the piston rod.
 14. An administration apparatus for medical use as defined in claim 13 wherein during the air releasing operation, the piston rod is moved at a speed lower than the speed of the piston rod during drug administration.
 15. An administration apparatus for medical use as defined in claim 14 wherein the low-speed operation of the piston rod during the air releasing operation is performed by PWM (Pulse Width Modulation) control for controlling the piston rod with the ON-OFF ratio of the pulse width being varied.
 16. An administration apparatus for medical use as defined in claim 14 wherein the low-speed operation of the piston rod during the air releasing operation is performed by voltage control.
 17. An administration apparatus for medical use which performs administration of a drug using an electric driving source, said apparatus comprising: a drug cartridge having an end closed with a plunger, and containing a drug inside; a cartridge holder for holding the drug cartridge; a piston rod for pressing the plunger in the drug cartridge to move the plunger; a needle assembly for inserting a needle into a target region, and administering the drug that is emitted from the other end of the drug cartridge with a movement of the piston rod; and a control circuit for performing control so that an air releasing operation for the drug cartridge and/or the injection needle is always carried out before performing the drug administration operation.
 18. An administration apparatus for medical use as defined in claim 17 further including an air releasing switch for performing the air releasing operation, and an administration switch for injecting the drug, wherein the control circuit permits an operation by turn-on of the administration switch after the air releasing operation.
 19. An administration apparatus for medical use as defined in claim 12 further including a contact sensor for detecting whether a portion of the administration apparatus in the vicinity of the needle assembly contacts a target region or not, wherein the air releasing operation is suppressed when the contact sensor contacts the target region.
 20. An administration apparatus for medical use which performs administration of a drug using an electric driving source, said apparatus comprising: a drug cartridge having an end closed with a plunger, and containing a drug inside; a cartridge holder for holding the drug cartridge; a piston rod for pressing the plunger in the drug cartridge to move the plunger; a needle assembly for inserting a needle into a target region, and administering the drug that is emitted from the other end of the drug cartridge with a movement of the piston rod; a dose setting circuit for setting, by a user, a dose of drug to be administered; a dose holding circuit for holding doses of drug which have been administered in the past; a dose comparison circuit for comparing the dose that is set by the dose setting circuit with the doses that are held in the dose holding circuit; and a control circuit for performing control so as to suppress the operation of the piston rod when the result of comparison by the dose comparison circuit is equal to or larger than a predetermined value.
 21. An administration apparatus for medical use as defined in claim 20 wherein the dose holding circuit holds the dose of drug that has been administered most recently, and the dose comparison circuit compares the dose that is set by the user with a dose that has most recently been administered.
 22. An administration apparatus for medical use as defined in claim 20 wherein the dose holding circuit holds the doses of drug of plural times of administrations performed in the past, and the dose comparison circuit compares the dose that is set by the user with a dose that is obtained on the basis of the plural times of administrations performed in the past.
 23. An administration apparatus for medical use as defined in claim 22 wherein the dose obtained on the basis of the plural times of administrations performed in the past is an average of doses of the plural times of administrations in the past.
 24. An administration apparatus for medical use as defined in claim 20 further including a notification unit for notifying the user that administration is not possible, when the result of comparison by the dose comparison circuit is equal to or larger than the predetermined value.
 25. An administration apparatus for medical use as defined in claim 24 wherein when the user permits administration of the dose of drug that is set by the user is permitted after notifying the user that administration is not possible using the notification unit, the control circuit cancels restriction on the operation of the piston rod.
 26. An administration apparatus for medical use which performs administration of a drug using an electric driving source, said apparatus comprising: a drug cartridge having an end closed with a plunger, and containing a drug inside; a cartridge holder for holding the drug cartridge; a piston rod for pressing the plunger held in the drug cartridge to move the plunger; a needle assembly for inserting a needle into a target region, and administering the drug that is emitted from the other end of the drug cartridge with a movement of the piston rod; a dose setting circuit for setting, by a user, a dose of drug to be administered; a dose detection circuit for detecting an actual dose of drug using an electronic circuit; and a comparison detection circuit for comparing the dose that is set by the dose setting circuit with the result of detection by the dose detection circuit to detect overdose or underdose of the drug.
 27. An administration apparatus for medical use as defined in claim 26 wherein the comparison detection circuit stops the piston rod when it detects overdose of the drug, thereby to stop administration.
 28. An administration apparatus for medical use as defined in claim 26 wherein the dose detection circuit detects the dose on the basis of the amount of movement of the piston rod.
 29. An administration apparatus for medical use as defined in claim 26 wherein the dose detection circuit detects the dose on the basis of the time when the piston rod moves at a constant speed.
 30. An administration apparatus for medical use as defined in claim 17 further including a contact sensor for detecting whether a portion of the administration apparatus in the vicinity of the needle assembly contacts a target region or not, wherein the air releasing operation is suppressed when the contact sensor contacts the target region. 